A febrile seizure is a convulsion in a child that may be caused by a spike in body temperature, often from an infection. Your child's having a febrile seizure can be alarming, and the few minutes it lasts can seem like an eternity.

Febrile seizures represent a unique response of a child's brain to fever, usually the first day of a fever. Fortunately, they're usually harmless and typically don't indicate an ongoing problem. You can help by keeping your child safe during a febrile seizure and by comforting him or her afterward.

Call your doctor to have your child evaluated as soon as possible after a febrile seizure.

Febrile seizure symptoms can range from mild — staring — to more severe shaking or tightening of the muscles.

A child having a febrile seizure may:

Have a fever higher than 100.4 F (38.0 C)

Lose consciousness

Shake or jerk arms and legs

Febrile seizures are classified as simple or complex:

Simple febrile seizures. This more common type lasts from a few seconds to 15 minutes. Simple febrile seizures do not recur within a 24-hour period and are generalized, not specific to one part of the body.

Complex febrile seizures. This type lasts longer than 15 minutes, occurs more than once within 24 hours or is confined to one side of your child's body.

Febrile seizures most often occur within 24 hours of the onset of a fever and can be the first sign that a child is ill.

When to see a doctor

See your child's doctor as soon as possible after your child's first febrile seizure, even if it lasts only a few seconds. Call an ambulance to take your child to the emergency room if the seizure lasts longer than 10 minutes or is accompanied by:

Vomiting

A stiff neck

Breathing problems

Extreme sleepiness

A high body temperature causes most febrile seizures.

Infection

Usually the fevers that trigger febrile seizures are caused by a viral infection, less commonly by a bacterial infection. Viral infections such as the flu and roseola, which often are accompanied by high fever, appear to be most associated with febrile seizure.

Post-immunization seizures

The risk of febrile seizures may increase after some childhood immunizations, such as the diphtheria, tetanus and pertussis or measles-mumps-rubella vaccinations. A child can develop a low-grade fever after a vaccination. The fever, not the vaccination, causes the seizure.

Factors that increase the risk of having a febrile seizure include:

Young age. Most febrile seizures occur in children between 6 months and 5 years of age. It's unusual for children younger than 6 months to have a febrile seizure, and it's rare for these seizures to occur after 3 years of age.

Family history. Some children inherit a family's tendency to have seizures with a fever. Additionally, researchers have linked several genes to a susceptibility to febrile seizures.

What tests does my child need? Do these tests require special preparation?

Is this likely to happen again?

Does my child need treatment?

Will giving my child fever-reducing medications during an illness help prevent febrile seizures?

What should I do the next time my child has a fever?

What can I do to help my child during a febrile seizure?

My child has another health condition. How can we manage them together?

Are there brochures or other printed material I can take? What websites do you recommend?

Don't hesitate to ask other questions, as well.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

Did your child have a fever or illness before having this seizure?

Can you describe your child's seizure? What were the signs and symptoms? How long did the seizure last?

Has this happened before?

Does anyone in your family have a history of febrile seizures or seizure disorders?

Has your child been exposed to illnesses?

Does your child have a history of head trauma or a neurological disease?

What you can do in the meantime

If your child has another febrile seizure:

Don't restrain your child, but do place him or her on a safe surface, such as the floor.

Place your child on his or her side, keeping the face to the side and the lower arm extended under the head, to prevent your child from inhaling vomit if vomiting occurs.

If your child had anything in his or her mouth when the seizure began, remove it to prevent choking. Don't put anything in your child's mouth during a seizure.

Seek emergency care for a seizure that lasts longer than 10 minutes.

Identifying the cause of your child's fever is the first step after a febrile seizure.

Simple febrile seizures

To determine the cause of infection, your doctor may recommend:

A blood test

A urine test

A spinal tap (lumbar puncture), to find out if your child has a central nervous system infection, such as meningitis

Complex febrile seizures

For complex febrile seizures, your doctor also may recommend an electroencephalogram (EEG), a test that measures brain activity.

If the seizure involved just one side of the child's body, your doctor may also recommend an MRI to check your child's brain.

Most febrile seizures stop on their own within a couple of minutes. If your child has a febrile seizure that lasts more than 10 minutes — or if your child has repeated seizures — call for emergency medical attention.

More-serious episodes

If the seizure lasts longer than 15 minutes, a doctor may order medication to stop the seizure.

If the seizure is prolonged or accompanied by a serious infection or if the source of the infection can't be determined, then your doctor may want your child to stay in the hospital for further observation. But a hospital stay isn't usually necessary for simple febrile seizures.

If your child has a febrile seizure, stay calm and follow these steps:

Place your child on his or her side on a surface where he or she won't fall.

Stay close to watch and comfort your child.

Remove hard or sharp objects near your child.

Loosen tight or restrictive clothing.

Don't restrain your child or interfere with your child's movements.

Don't put anything in your child's mouth.

Time the seizure.

Most febrile seizures occur in the first few hours of a fever, during the initial rise in body temperature.

Giving your child medications

Giving your child infants' or children's acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others) at the beginning of fever may make your child more comfortable, but it won't prevent a seizure.

Use caution when giving aspirin to children or teenagers. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in such children.

Prescription prevention medications

Rarely, prescription anticonvulsant medications are used to try to prevent febrile seizures. However, these medications can have serious side effects that may outweigh any possible benefit.

Oral diazepam (Valium), lorazepam intensol, clonazepam (Klonopin) or rectal diazepam (Diastat) may be prescribed for children who are prone to febrile seizures. These medications are typically used to treat seizures that last longer than 10 minutes or if the child has more than one seizure within 24 hours. They are not typically used to prevent febrile seizures.

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